FIG. 1 shows a wireless mesh network. The network includes wireless access nodes 130, 140, 150, 160, 170 that provide data paths between a client 180 and gateways 110, 120. The gateways 110, 120 are connected to an upstream router 105, which can be connected to the internet 100.
As shown, the client 180 can roam from a first access node 160 to second access node 170. The first access node 160 is associated with a first cluster of a first gateway 110, and the second access node 170 is associated with a second cluster of a second gateway 120.
When the client 180 associates with an access node of a cluster, the gateway of the cluster sends a gratuitous (address resolution protocol) ARP to the upstream router 105. ARP is a protocol for the resolution of IP addresses to MAC addresses. The gratuitous ARP provides the upstream router 105 with an updated ARP cache entry associating the IP address of the client 180 to a MAC address of the gateway 120, so that the upstream router 105 knows where (which gateway) to send data traffic for the client. That is, the upstream router 105 sends the traffic to the gateway connected to the client based on the last received gratuitous ARP. In addition, the gateway 120 subsequently performs proxy ARP on behalf of the client 180 as long as the client remains within the cluster of the gateway 120. A proxy ARP entails the gateway 120 responding to ARP requests from the upstream router 105 for the IP address of the client 180 with a response containing a MAC address of the gateway 120.
Initially, the client 180 of FIG. 1 attaches to the first cluster and the first gateway 110 sends a gratuitous ARP. When the client 180 roams to second access node 170 of the cluster of the second gateway 120, the second gateway 120 sends a gratuitous ARP to the upstream router 105, which obsoletes the gratuitous ARP previously sent by the first gateway 110. Again, the upstream router 105 sends the traffic to the gateway connected to the client based on the last received gratuitous ARP. In this way, client mobility can be supported without requiring any special mobility software on the client and without requiring any non-standard behavior on the upstream router.
It is desirable to extend this mobility to address a scenario where an upstream router is separated from the gateways 110 and 120 by an intervening Layer 3 TCP/IP network. It is desirable to be able to do this while continuing to require no special mobility software on the client and no non-standard behavior required of the upstream router. It is also desirable to ensure that all traffic from the client be forced through the upstream router 105. The mesh network of FIG. 1 is limited because this configuration does not provide for client roaming when the upstream router is remotely located. A remotely located upstream router can advantageously provide services, such as authentication, authorization, accounting, subscriber management including per-user bandwidth controls, and dynamic host configuration protocol (DHCP) services. The DHCP server dynamically provides IP address assignments to client devices through the dynamic host configuration protocol. The dynamic host configuration protocol is a protocol for assigning dynamic IP addresses to devices on a network.
It is desirable to have an apparatus and method of client roaming between different clusters of a wireless mesh network. It is desirable that gateways of the wireless mesh network be connected to an upstream router through a layer three network, and be remotely located.